Profile: 42k

I've set the first Column to KEY (GTIN)
The first column in my csv-file is the GTIN

Every time i parse the file new products is created. I want them to be created the first time and then updated, what could be wrong?

I doesnt understand how to import New products with Product Attributes

example
T-shirt
-----XL
------ S

We get a manufacturer file looking kindof like this:
gtin;Name
701010101;T-shirt XL
701010102;T-shirt S

How should the file look like on my part?